Are there any other Earths out there? Is there another planet like ours, maybe one where we could live? One goal in the search for exoplanets, planets orbiting stars other than our own sun, is to find Earth-like planets. NASA’s Kepler mission just found the closest match yet!

This planet is called Kepler-452b. It’s not exactly a catchy name, but it’s informative: the name tells us the planet was found by the Kepler mission, and gives a number to the star system and a letter to each object. This planet got the letter “b” because it’s the second object found in the system, after the star.

A planet in its star’s habitable zone? We’ve found a few, but that’s still pretty cool—or rather, just the right amount cool for liquid water to potentially exist on the planet. This is the definition of the habitable zone. Without liquid water, we wouldn’t find a planet habitable, and in order to have liquid water, a planet would need to be warm enough for water not to freeze and cold enough for water not to boil. The temperature on the surface of a planet depends largely on its distance from its sun. The closer they are, the warmer the planet is. However, being not too close to and not too far from its star doesn’t tell you everything about a planet. It could be large or small, and made of all sorts of different materials. It could be dense and rocky like Earth or Mercury, or it could be fluffy and gaseous like Jupiter or Neptune.

So, being in the habitable zone isn’t enough to make a planet habitable. It would be hard to live on a planet without a surface you could stand on, so if you’re looking for a new planet to inhabit, pick out a rockier one. The size of the planet would also make a difference. The smaller a planet is, or even a moon for that matter, the harder it is to hold on to an atmosphere. Less mass means less gravity, which means less pull on the gases which make up an atmosphere. Gas particles can fly away over time until there are hardly any left. More mass means more pull, so it’s harder for particles to escape. So, more massive planets are more likely to have a thick atmosphere.

What about Kepler-452b? Where does this recent discovery fit in? It’s 60% larger than Earth in diameter, which is actually pretty close in size. For comparison, Kepler-452b is about 1.6 times the diameter of Earth, and Earth is about 1.9 times the diameter of Mars. Kepler-452b is considered a super-Earth in size. That’s what we call planets near in size to Earth, but on the large side.

While we know all this about Kepler-452b, there is also a lot we don’t know. We don’t know exactly what it looks like. We don’t know how close it is to actually being habitable. We certainly don’t know its whole story—yet. As technology improves, telescopes get better, and we think up cleverer ways to learn more about far-off places, we keep finding out more and more about distant worlds like this one.

In this episode, we meet Dr. Dante Lauretta, Professor of Planetary Science at the University of Arizona and Principal Investigator for the OSIRIS-REx mission.

I’ve talked about the OSIRIS-REx mission before, and it’s one of the coolest things going on in exogeology: they’re going to send a spacecraft to an asteroid and bring back a piece. Wonder what it’s like to be in charge of all of that? Watch the video below to find out!

Could you land on a comet? Normally, the force of gravity holds a lander to the surface of a larger body, like a planet or a moon. The less mass an object has, the less gravity pulls you toward it. Comets are small. Gravity won’t do you a lot of good, so you would need to hang on tight.

That’s what Philae is doing. The European Space Agency (ESA) sent a spacecraft named Rosetta to Comet 67P/Churyumov–Gerasimenko, and Rosetta carried a dishwasher-sized probe called Philae, which was to land on the comet. The comet is about the size of a mountain, which may seem big, but think how small a mountain is in comparison to a planet! The Philae lander had to come equipped with screws in its feet and harpoons to grasp the surface.

Philae detached from Rosetta early this morning (09:03 GMT, 02:03 Arizona time) and began its descent. Curiosity had seven minutes of terror landing on Mars, but Philae took seven hours from separation to landing. At 16:03 GMT, ESA heard from the little lander. Philae had successfully touched down! But remember those harpoons? They didn’t work. Philae is clinging on by the screws in its feet, but it’s there.

Philae’s view of the comet. Courtesy ESA.

Philae will photograph and analyze the comet for the next two and a half days. If it gets enough sunlight for power, it can keep going for an “extended phase” lasting until March 2015—four whole months of comet science! After that, the comet will be closer to the sun and Philae will probably be too hot to work. Comet 67P/Churyumov-Gerasimenko will also heat up as it gets closer to the sun, so we might be able to see it active, with ices sublimating (turning from solid to gas) and creating the tails of gas and dust comets are famous for. Maybe the most exciting reasons to study a comet up close are that we get to see way, way back in history, and we get to learn about the far, far off outer solar system. Here’s wishing Philae just the right amount of sun.

Is landing on a comet even possible? Yes, but it’s tricky. Hang on tight, Philae!

Awesome news: the countdown for the OSIRIS-REx asteroid sample return mission has begun, and it’s now only 996 days until the beginning of the launch window!

Want to know more about asteroids and sort the science facts from the science fiction? The 321Science team is here to help with a video to illustrate the difference and answer a few questions about asteroids.

I’m incredibly excited about this video, which I helped to make! It was interesting seeing it go from script to numerous drawings to super-cool final product. I drew a couple of scale bars and small asteroid, placed a couple paper planets, and did a few miscellaneous other things. Also, keep your eyes peeled for a certain spaceship from a long time ago in a galaxy far, far away…

Today at 1:28 EST at Cape Canaveral, MAVEN successfully launched, and it’s now on its way to Mars.

MAVEN is a NASA mission to study the upper atmosphere of Mars. Its name stands for Mars Atmosphere and Volatile EvolutioN. The “volatile” part refers to compounds like CO2 (carbon dioxide), N2 (nitrogen), and H2O (water). MAVEN plans to gather clues about how those were lost over time. Once the MAVEN spacecraft reaches Mars, it will orbit the planet and use many different sensors to learn more about its atmosphere, and how it interacts with the sun and solar wind.

This is it, the very last clue of the whole second game. If you’ve been paying abnormally good attention, you’ll have noticed this is clue number 61. It’s hard to believe the game is nearly over already. We’ve been to so many cool places! But, alas, there has to be an end to this game. Tomorrow will mark the official end of game 2, when we reveal the correct response to today’s final clue.

The category: Musical Groups. Drumroll please!

(Note that the music in the background isn’t necessarily by the band that’s the correct response.)

Click here to watch game one and ALL 60 previous clues of the current game. (And maybe even a third game in the future.)

This game has taken us all over the country for all sorts of different categories. The Mishmash category alone features everything from elements in California to the world’s biggest ball of twine by one man in Minnesota, and more! This exemplifies one of my favorite things about the whole 60 clues of this Geo Party! game: variety.

Has it really been 60 clues already? Wow. Keep tuning in though—there’s still a final clue to look forward to!

Our most recent category: The Monterey Bay Aquarium! This place has a lot of potential for clues, and narrowing down all the possibilities to 5 was a challenge.

Speaking of challenges, I wasn’t the most eager to touch the creature in clue 4, until my crew suggested it could be a clue. Trivia clues are a pretty good excuse to try new things, don’t you think? Yet another challenge was that some of the exhibits made filming more difficult due to lighting, noisy crowds, and reflective glass, among other reasons. I was hoping to have a clue on seahorses, but do you have any idea how hard it is to get them on camera non-blurrily? Even still, there were a few times when we managed to get some great videos, like my favorite, the giant octopus in clue 5.

Our most recent category sent us to the Tech Museum of Innovation, a science museum in San Jose, California, where we learned about all sorts of things, from astronauts to the light spectrum. My favorite part was filming the first clue on an earthquake simulator!

All aboard! We took a trip this week starting in Chicago, Illinois and heading west on Amtrak’s Empire Builder line. I got to roll along through several states I’d never been to before as I rode this train, and the views were slightly snowy and quite nice. What do you know about the towns along the path of the Empire Builder?

This was the third week of Zoe’s Geo Party! Game 2, featuring the novel Divergent by Veronica Roth. Special thanks to Veronica Roth for writing an excellent story which inspired me to make trivia clues about it—when I knew I would be going to Chicago last November, I just had to seek out places from her book.

On the ferris wheel in Chicago.

This category took us to real locations also used as settings for the fiction story. (Hmm, that sounds familiar.) Visiting places where my favorite stories take place is a bit surreal, but in a good way. What’s your favorite story set somewhere you’ve been? Miss a clue? Rewatch all five with the links below:

This week was the second of Zoe’s Geo Party! Game 2, revealing a category on the Computer History Museum in Mountain View, California. When I arrived at the museum, I knew I’d find enough material for a category. What I didn’t know was that I’d be so fascinated that I’d have to rush at the end of my visit to see everything before closing time. If you find yourself nearby, it’s worth taking some time to walk through.